The paper length is not relevant since the chart flows from one page to the next.
Mobile
in.
mm
Portrait
2.75
70
For smart phones, not for printing
Landscape
5.5
140
For smart phones, not for printing
USA & Canada
in.
mm
Letter Portrait
8.5
216
Also Legal Portrait
Letter Landscape
11
279
Legal Landscape
14
356
Also Ledger Portrait
Ledger Landscape
17
432
International
in.
mm
A5 Portrait
5.82
148
A4 Portrait
8.25
210
Also A5 Landscape
A4 Landscape
11.71
297
Also A3 Landscape
A3 Landscape
16.54
420
The Text+ programs assume that the right and left margins are each about 25mm (1/2 inch) wide.
On the Format for Printing page, differences in page margins can be accommodated by the "fudge factor":
Smith OGDEN
(Cowling, Yorkshire, England;11 Feb 1821 - 19 Dec 1892)
Dinah SMITH
(Cowling, Yorkshire, England;9 Dec 1821 - 24 May 1885)
├─Hannah OGDEN
(Cowling, Yorkshire, England;Between Apr and Jun 1861 - 14 Mar 1934)
│ Thomas WILKINSON
(Cowling, Yorkshire, England;Abt 1854 - 1927)
│ └─Smith WILKINSON
(13 Sep 1890 Cowling, Yorkshire, England - 27 Nov 1949 Yorkshire, England)
│ Hilda OVEREND
(21 Feb 1898 Keighley, Yorkshire, England - 30 Oct 1976 Yorkshire, England)
│ └─Kathleen WILKINSON
(14 Aug 1931 England - 18 Dec 2018 Yorkshire, England)
1821 - 1892 (71 years)
Frederick COCKCROFT 
(26 Apr 1911 Burnley, Lancashire, England - Apr 1995 Morecambe, Lancashire, England)